Electrolytic method



MLM. MERRITT.

ELECTROLYTIC METHOD, APPARATUS, AND PRODUCT.

APPLICATION FILED APR. 15. I9l9.

Patented Nov. 18, 1919.

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M. M. MERRITT.

ELECTROLYTIC METHOD,JAPPARATUS, AND PRODUCT.

APPLICATION FILED APR. 15, I919.

Patented Nov. 18, 1919.

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APPLICATION FILED APR. 15. 1919.

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MASSACHUSETTS.

ELECTROLYTIC METHOD, APPARATUS, AND PRODUCT.

To all whom it may concern:

Be it lmown that I, MATTHEW M. MERRITT, a citizen of the United States, and a resident of 'South Middleton, county of Essex, State of Massachusetts, have invented an Improvement in, Electrolytic Methods, Apparatus, and Products, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

This invention pertains to improvements in electrolytic methods, apparatus and products. One of the broader aspects of the invention relates to methods and apparatus for depositing metal electrolytically while the electrolyte flows in a stream past the cathode or cathodes, the anodes preferably being distributed in the stream longitudinally thereof and preferably in comparatively close relationship to the cathode surface or surfaces.

Another aspect of the invention relates to the circulation of the electrolyte in such a way that an opportunity is afforded for the same to rest so that hydrogen may have an-opportunity to escape from the body. of the electrolyte during a period when the electrolyte is not beingused actively as an electrolytic agent.

Another aspect but preferably by permitting the electrolyte to fall through the air a suflicient distance to accomplish this purpose.

While the most important features of my invention are of general application in the electrolytic art, and are useful in making all electrolytically deposited or coated art1- cles or products, I have elected, without limitation thereto, to disclose the same inconnection with the deposit of metal on elongated cathodes in connection with the manufacture of electrolytically coated wire and similar roducts such as tubes formed by electrolytlcally depositing metal on elongated cathodes adapted to be removed after electro-deposition, leaving the electrolytically deposited shell to form the tube or pipe. Where my invention is applied to the manufacture of coated wire, tubing or pipe, it preferably includes the passage of the wire or other cathode through the electrolytic Specification of Letters Patent.

of the invention includes the aeration thereof in any suitable way,

.deposition takes place,

bath so that each portion of an elongated flexible cathode may be, if desired, subjected to electrolytic" action under substantially constant conditions and for substantially the same length of time. 4

While many features of my invention are of general application, and may be used for any purpose in connection with the deposition of any metal on any form of cathode, I

Patented Nov. 18, 1919. Application filed April 15, 19 19. Serial No. 290,152. I

have elected in this application specifically to describe the same in connection with the electro-deposition of copper on a steel cathode, of copper on an aluminum cathode (preferably treated as hereinafter .more fully described), and in connection with the electro-deposition of copper on a fusible or otherwise removable cathode, the latter being primarily useful in connection with the formation of tubing.

(The drawings show an illustrative embodiment of a preferred form of apparatus useful in connection with practising my improved process as applied, to the manufacture of wire, tubing and the like.

Figure 1 is in elevation,. illustrating diagrammatically certain preferred forms of apparatus used in performing certain preferred preliminary steps of my method;

Fig. 2 is a side elevation showing a preferred form of apparatus for use in connection with'practising my improved method where applied to the manufacture of wire and tubing, the apparatusdisclosed in Fig. 2 being that in which the principal electropreferably subsequent to suitable treatment, hereinafter described, of the anode material by the apparatus shbwn in Fig. 1;

' Fig. 3 is a plan of the in Fig. 2;

Fig. 4 is a section on the line 4-4 of Fig. 5 is a section on the line 5- 5 of Fig. 2; and

. Fig. 6 is a section through a preferred form of apparatus for removing the fusible cathode material from tubing made by my method and apparatus.

I will first describe rather specifically,

apparatus shown though without limitation of the broader a longitudinal section, partly aspects of my invention, the operation of the apparatus shown in the drawings in connection with the manufacture of copper coated steel wire. Steel, iron or other suit- 5 able wire 7, preferably coiled on a drum 8 t -7 may be drawn from'the drum 8 and initially passed through a cleansing agent, preferably muriatic acid and tin chlorid in the tank 9, the- Wire thence passing under a stream of water 10 to remove any acid which may cling to the surface thereof, and thence into an alkaline bath, preferably cyanid, 1n the tank 11. This bath 11 is preferably provided with a suitable anode 12, which may be of copper, a negative connection 13 being made to the wire preferably before entering the bath 11. The wire maybe fed at any suitable speed, but is preferabl Immersed in the cyanid bath 11' for a su clent length of time to plate the wire with copper so as to protect the steel from the subsequent action of the acid when deposition is earned on in an acid bath as hereinafter described. The current density used in connection with plating in this cyanid bath may be as is usual in copper plating processes. After the Wire leaves the cyanid bath 11, it 1s again Washed, preferably by passlng through a glass tube 14 into which a stream of water is introduced at 15, this providing a very simple and efficient wire, thus plated in the cyanid bath and rinsed, is then passed to the apparatus in which further electro-deposition of metal is rapidly carried on under high current density.

Perhaps the most important feature of my improved apparatus and method, which feature is applicable to all kinds of electrodeposltion of all metals on all forms of cathode. includes the passing of the electrolyte 1n a stream past the cathode. This stream may conveniently be confined in a trough, which may, if desired, slant in two dlrections as best shown in Fig. 2, the electrolyte being introduced into the trough at 16 and flowing in opposite directions through the trough or troughs 17 '18 and thence flowing into a reservoir or tank 19. The discharge ends of the troughs are preferably at a suflicient distance above the level of the electrolyte in the tank or reservoir 19 to afford a fall of the electrolyte through the air. The tank or reservoir 19 affords a chance for the escape of hydrogen from the electrolyte and is preferably of sufficient depth to permit settlement of any heavy impurities to the bottom and to permit any lighter impurities, such as hydrogen, to rise to the top, while leaving a middle stratum of comparatively pure electrolyte, from which is drawn the supply of electrolyte to the discharge 16, the circulation preferably being effected by any suitable elevating means, I herein shown as a centrifugal pump 20. To

rinsing medium. The

increase the conductivity of the electrolyte, and to facilitate the escape of hydrogen bubbles, I preferably provide a steam coil or other heating agent for heating the electrolyte in the tank 19.

It should be clearly understood that the apparatus illustrated is merely a preferred embodiment of my invention, and that various features thereof and various steps of the method used in connection therewith are useful, whether used in combination with other portions of the apparatus and other steps of the method, or whether used separately in any connection. For instance, While I have shown the trough sloping in two directions, it is obvious that a trough sloping in one direction, or any means or suitabe mechanism for producing a flow of the electrolyte, is of use. It is also clear that, while I have shown the flow of electrolyte in connection with the electro-deposition on wire, that the How of the electrolyte is useful when used in connection with cathodes of any kind, whether individual articles continuously immersed in the flow, or whether individual articles intermittently immersed in the .fiow. It should also be understood that the preferable aeration of the electrolyte, while preferably provided by the fall of the electrolyte from the end or ends of the trough or troughs, may be effected in other ways, and that the provision of means for permitting the electrolyte to rest, preferably while heated, may be of'use in connection with electrolytic processes differing greatly in other details from those herein described. Similarly, while the various features of my apparatus and steps of my method are peculiarly useful in their cooperative relationship, it should be understood that each may be of use in other connections.

Returning to the specific embodiment of my invention shown in the drawings, the wire 7 preferably passes through the trough or troughs 17, 18 a plurality oftimes, being passed preferably in a generally helicoidal relationship about a series of preferably independently rotatable sheaves arranged in tiers 21, 22 at opposite ends of the troughs, thus providing. a continuous length of wire making up two runs, each run preferably including'several passages of the wire. The runs correspond to the opposite sides of a helicoid viewed as a whole, and the several passages of the wire making up each run correspond to the individual turns making up the sides of the helicoid. The tiers of sheaves 21 and 22 may be conveniently used as negative contacts for conducting the current rendering the wires carried by the sheaves the cathodes of the apparatus.

In order to provide for close proximity of the anode material to the wire, I preferably duplicate the troughs 17 18, providing cortroughs 17 posed of copper sheets or copper scrap retaine'd behind perforatedl lead sheets 40. Any suitable ,positive connection may be made with those over which the wire is passed,

anodes or with the lead screens before referred to, or with the lead lining of the troughs. It is obvious that, if desired, I may provide any desired number of runs by changing the arrangement of sheaves and in such case I may provide a correspondingly increased number of troughs. It is also obvious that the depth of the troughs may be increased or decreased to correspond to an increase or decrease in the number of passages of the wire making up each run. The troughs may but I have found by experiment sloping in one direction thirty feet long, and having a fall of four inches, are satisfactor twd directions, as shown on the drawings, thirty feet long and having a slope of two inches toward each end thereof, provides a very desirable rate of flow, approximating preferably one hundred and thirty feet per minute,

I have shown in Fig. I a cross-section on the line 4.4 of Fig. *2, Fig, I being on an enlarged scale and showing details of the troughs and cooperating parts adjacent the center of the apparatus. Where troughs sloping in two directions are used, Imay provide suitable separating means for the wires to prevent contact of one against the other, herein shown as glass rollers" 25.

adapted to be While I preferably make myprocess a continuous one, joining one roll of wire to the next, it is sometimes necessary to suspend operations and to pass a new wire through as distinguished from a drawing, operation,. To facilitate this, I have provided mechanism, best shown in Figs. 2 and 5, for dropping "the tanks away from their operative position so as to permit ready passage of the wire about the sheaves and through the rollers 25.

pinions 27 27 mounted on shafts 28, 28 and adapted to be turned by cranks 29, 29 and locked against undesired rotation by any suitable mechanism, typified or troughs for each run I the dog ofthe wire. Thus,

As best the anodes may be com-' suitable screens such as the be of any suitable length, that troughs and similarly that a trough sloping in To facilitate raising and lowering" of the tanks, I have shown racks 26, 26 cooperating. with or pawl 30." The troughs 17 and 17 may be guided in their vertical movement in any suitable way, typified. by the guides 31, 3'1 engaging vertical members of a bridge or framework 32 passing above the-troughs and supported or guided at their inner-sides by rollers 33. The glass rollers 25, herein before described, are preferably suspended in frameworks 3%, 34 from the bridge 32, which may conveniently also support the discharge conduits or nozzles16, 16.

As heretofore stated, he current density utilized in connection with the troughs is preferably much higher than the current density utilized in connection With the cyanid bath 11. The rate of deposit onthe various portions of the wire exposed to electrolytic action in the troughs varies in proportion to. the length of time that the various parts of the wire have been expose to electrolytic action, the wire as it first enters the trough after being washed pursuant to the cyanid bath covered by the cyanid plating operation, and being of comparatively small cross-section and of comparatively slight electrical conductivity as compared with the cross-section and electrical conductivity after considerable electro-deposition has taken place. in the troughs. It may be roughly said that the wire at any given time exposed to. electrolytic action in the troughs takes the form of a truncated cone, is at the beginning and the large end at the finish. Of course, as the operation is continuous, each portion of the wire being subj ected to exactly the same treatment as each other portion, the'wire as it leaves the finishing point is of uniform diameter and conductivity.

The power for conducting or drawing the wire through the various operations heretofore described may be applied to the winch 35, about which the wire is passed before passing on to a winding drum 36 which is driven through a clutch adapted to slip to compensate for changes in diameter of the drum as the wire is wound thereon. The winch 35 determines the speed at which the wire passes through-the apparatus.-

being only slightly of which the small end for Just before the wire goes onto thewinch,

it is preferably washed by washing apparatus 37. 9

Where the apparatus is used for the deposition of copper on a cathode composed of aluminum wire, the acid bath 9 and the cyanid bath 11 need not be used, but some mechanism should be provided for treating the surface of the aluminum wire toremove the oxid on the surface of the aluminum and preferably to deposit a film of foreign substance to serve as an oxid-excluding medium over the surface of the aluminum, and to provide a surface thereto other than aluminum which will readily take in a satstance coated with a isfactory manner the deposit of copper or other metal during subsequent electrO-deposition'. The 'oxid-excluding medium is preferably tin, and I may effect the combined deoxidizing'and tinning operation by supplying the pipe 15- with a mixture of muriatic acid, water and tin chlorid. To obviate the necessity for too rapid circulation of this liquid, I may provide-a sponge on the interior of the tube14 to absorb and check the flow of the cleansing and coating agent, it beingnecessary only to supply a sutiicient quantity thoroughly to clean and coat the surface of the aluminum wire. 7

While I have described this preliminary treatment of aluminum prior to electrodeposition in connection with the manufacture of a continuous strand of wire, and while this method isv of great utility in this connection, it will be understood that this feature of my invention may be useful in other connections such as the preparation of any object made of aluminum or surfaced with aluminum for electro-deposition. The interposition of the coatin of oxid-exclud ing medium between the afi minum and the copper minimizes'that galvanic deterioration of these metals which normally arises where, in the presence of even a trace of moisture, copper and aluminum are permitted to come into contact or even into close proximity.

here my improved method and apparatus is used in connection with the manufacture of tubing and pipes, a cathode of fusible metal or any other suitable conductive substance, or even a non-conductive subv conductive substance, is substituted for the initial coil of steel wire on the drum 8. Where this readily fusible or otherwise removable core or cathode is composed of lead or an alloy of tin and lead or the like,.it is not essential that any preliminary treatment be given prior to starting of electro-deposition in the flowing electrolyte, but where it is desired to provide a tube having an interior coating of tin, I may pass the cathode through an alkaline .bath, corresponding to the cyanid bath 11, in which'I electrolytically deposit copper on the surface of the fusible metal cathode prior to the electro-deposition of copper or other metal in an acid bath. passage of the cathode through the flowing electrolyte may be the same as in the case of coating wire. as hereinbefore described, and after elect-ro-deposition is completed the cathode with the electro-deposited metal thereon may be wound in the form of a helix and placed in a melting furnace, shown in Fig. 6, the entire coil being heated to .a point suflicicnt to melt the readily fusible core, but not sufiicient to melt the copper surface, and air pressure being ap plied at 38 to blow the melted fused core possible, while The I from the interior of the tube. Where the initial deposit of copper on the fusible cathode has been made in a cyanid bath, as hereinbefore described, the interior surface of the copper is chemically clean at the time when the fusible core is melted out, and the tin or similar content in the fusible 'core will adhere to the interior surface, thus providing a perfectly smooth and perfectly tinned lining to the tube. 4

vThe use of an electrolyte which is flowing during electro-deposition enables me to use a much higher current density than has been securing satisfactory results, in any electro-depositing process heretofore considered possible. I have secured fine.- grained, smooth, ductile, uniform, homogeneous electro-deposits in connection with this method and apparatus while using a current density up to one thousand amperes per square foot of cathode surface. Up to the present time a current density of fifty amperes per square foot has been considered the highest possible limit and in practice it has been necessary to utilize still lower densities. An increase in density has resulted in a spongy texture and brittleness in the deposited product. As the amount of metal deposited varies directly with the current density, it is obviously of advantage to utilize high amperages if consistent with quality of product. While not limiting myself to any particular theory of operation concerning the practical results which I have empirically demonstrated, I may say that I believe that the possibility of utilizing currents of high density is due to the rapid flushing of the bath by a substantially unitary stream of electrolyte which not only prevents or minimizes ionic localization but breaks up and carries away any bubbles of hydrogen, and furthermore acts to cool the wire which would otherwise be unduly heated by the high current. The continuous cooling by therapid stream of liquid maintains the electro-chemically active portion of the bath at a moderate temperature, preventing the deposit of spongy and flocculent material which takes place at elevated temperatures. The provision, fur-" thermore, of a large body of electrolyte which is chemically inactive or at rest and the utilization of a small portion of this delivered in such a manner as to flush the electrodes facilitates the utilization of a high density current, probably because it.

active bath to the resercathode, commonly known as spongy deposit, are present where my apparatus and process is utilized. This is due to rapid liberation of the hydrogen arising from several-causes, first, the rapid passage of the electrolyte past the cathode surface; second, the fact that no given portion of the electrolyte is actively used continuously for any considerable length of time; third, the fact the electrolyte acts that no given portionof more than momentarily on any 'ven portion of the cathode surface; fourt the fact that the electrolyte is given'an opportunity to rest between the periods of recurrent use of any portion thereof, thus providing a' time for liberation of the hydrogen and for settlement of any foreign substance heavier than the electrolyte; fifth, the fact that the reservoir 19 provides an opportunity for-a lower stratum in which the impurities can settle, an upper stratum in which the hydrogen can be liberated, and an intermediate stratum comparatively clean from which the supply of electrolyte to the trough or troughs can be drawn; sixth, where the apparatus and method is used in connection with the manufacture of a, continuous article, such as specifically described herein, the preferably constant passage of the article through the electrolyte insures the absolute uniform treatment of all portions of the cathode, and if, for any reason, conditions exist in any part of the stream such as the absence of anode surface or irregularity of flow of the electrolyte adjacent the point of introduction of the electrolyte or elsewhere, this accidental or otherwise non-uniform condition will act uniformly upon all parts of the wire as it passes through the apparatus, insuring uniformity of product and insuring minimization of deleterious action on any given part of the wire; seventh, the provision of the relatively large reservoir 19 not only provides for rest of the bath, but also permits heating of the same for a considerable length of time between intermittent periods of use of any given portion of the bath.

' The amount of electrolyte actually subject to electrolytic action at any one time may be almost negligible in comparison with the amount of electrolyte in the reservoir.

The apparatus disclosed herein is claimed in a divisional application, 328,999, filed October 7, 1919. The aluminum wire product disclosed herein is claimed in a divisional application Serial No. 329,000, filed October 7, 1919. My application Serial No. 330,403, filed October 13, 1919, is in part a continuance of the present application, having claims specific 'to apparatus and methods for carrying on electro-deposition on separate objects immorsed in a stream of electrolyte. My ap plication Serial No. 330,404, filed October form of apparatus and Serial No.

13, 1919, is in part a continuance of the present. application, having claims to a method of preparing aluminum for soldering operations.

While Lhave shown in the drawings and described rather specifically a preferred a preferred method, it will be understood. that major changes involvin omission, substitution, reversal or other c anges in the apparatus as a, whole or in parts thereof, and ilar or greater scope in method, may be made without from the scope of my invention, best defined by the following claims.

Claims: 1. The electrolytic connection with the departing method characterized by deposition on a cathode in a bath circulating past the cathode in a rapidly flowing body substantially as a unit.

2: The electrolytic method characterized by deposition on a cathode in a bath constituting a relatively small portion of a supply of electrolyte circulating as a rapidly flowing body or unitary stream past the cathode.

3. The electrolytic method characterized by maintaining a relatively large supply of electrolyte not actively employed, withdrawing continuously-a portion thereof and discharging the same as a rapidly flowing substantially unitary stream past electrodes.

4. The electrolytic method characterized by maintaining a relatively large supply of electrolyte not actively employed, withdrawing continuously a portion thereof from its central portion in the horizontal plane, discharging the same as a substantially unitary stream past electrodes and returning said portion to the supply by permitting the stream to fall through the air.

' 5. The electrolytic method characterized even changes of, Sim-- which is p by deposition on a cathode while the electrodes are continuously flushed by a stream of electrolyte flowing at a rate of notless 7. The electrolytic method characterized by depositing a metal by a current of high density not less than one hundred amperes per square foot of cathode surface while ef- V fecting constant renewal of the electrolyte, from a relatively large supply thereof not actively employed, at a rate precluding ionic localization and maintaining the bath at a I stable temperature.

8. The electrolytic method characterized by depositing a metal by a current of high density not less than one hundred amperes 'lfO per square foot of cathode surface acting in an electrolyte passing the electrodes at a rate not less than forty feet a minute.

9. The improvement in the art of electrodeposition which comprises feeding an elongated cathode axially between closely arranged anodes while an electrolyte passes rapidly as a substantially unitary column between the anodes.

10, The improvement in electrolytic deposition which comprises providing a relatively large amount of electrolyte, said electrolyte being repeatedly circulated there being used actively for electro-deposition at any one time a relatively small proportion of said amount, any given portion of the electrolyte being used actively and continuously for a period less than a minute.

11. The improvement in electrolytic deposition which comprises subjecting only a portion of the bath to electrolytic action at any one time, while permitting the balance of the electrolyte to rest, the electrolyte flowing rapidly while subjected to electrolytic action, and being repeatedly circulated.

12. The improvement in electrolytic deposition which comprises using actively a portion of the bath for a relatively short time while in a rapidly moving stream and subjecting that portion of the bath so used to aeration prior to re-utilizat'ion thereof.

l3. The improvement-in electrolytic depos tlon which comprises using actively a portlon of the bath for a relatively short time while in a rapidly moving stream and subecting that portion of the bath so used to aerat on prior to re-utilization thereof by permlttlng an unconfined stream of the electrolyte to fall through the air.

4 The improvement in methods of electrolytrcally coating ferrous wire, which comprises initially plating said wire in an alkaline bath and subsequently depositing metal thereon under relatively high current densityin a rapidly flowing acid bath.

15 The improvement in electrolytically coating ferrous wire which comprises passmg the continuous wire first through an al.- kallne bath to plate the surface of the wire a rapidly flowing acid bath, without interruptlon of the progress of the wire.

16. The improvement in the manufacture 0f electrolytically coated wire which comprises subjecting a continuous length of said Wlre to successive difl'erent electrolytic depositing operations, while continuously advancing the wire in a direction longitudinal of its axis, initially to effect electro-deposition in an alkaline bath and subsequently to effect further electro-deposi-tion in a rapidly flowing acid bath, whilecontinuously advancing the wire in a direction longitudinal of its axis.

66 17. The improvement in electrolytic procand subsequentlypassing the wire through esses which comprises providing a relatively large amount of electrolyte and utilizing for active electrolytic deposition at any one time only a relatively small proportion of said electrolyte,,the electrolyte being heated and the utilized portion thereof being cir culated in a swift-flowing stream. j

18. The improvement in electrolyticprocesses which comprises providing a relatively large amount of electrolyte and utilizing for active electrolytic deposition at any, one time only a relatively small proportion of said electrolyte, the electrolyte while being utilized surging'past the cathode, said electrolyte being heated by a heating agent actin primarily on the proportion of the electrolyte which is not being actively used for electrolytic deposition.

19. The method of electrolytically coating an elongated flexible cathode which comprises initially passing said cathode through an acid cleansing agent, then rinsing said cathode to remove the acid therefrom, then plating said cathode in an alkaline bath, again rinsing said cathode, and then pass ing said cathode through a rapidly flowing stream of acid electrolyte rendered' active y a relatively high current density.

20. The method of electrolytically coating an elongated flexible cathode, which comprises plating said cathode in an alkaline bath, rinsing said cathode and then passing said cathode through, a rapidly flowing stream of acid" electrolyte rendered active by a relatively high current density.

21. The method of depositing metal on a flexible cathode which comprises repeatedly feeding the cathode through a rapidly flowing stream of the electrolyte, while using a current density exceeding fifty amperes per square foot.

22. The electrolytic method of depositing metal on flexible cathodes, which comprises winding a flexible cathode a plurality of times about two sets of sheaves to provide a helicoidal double run of wire, providing two rapidly flowing streams of electrolyte, one for each of said runs, and carrying on electro-deposition under a current density exceeding fifty amperes per square foot,

23. The electrolytic method of depositing metal on a wire or the like, which comprises winding the Wire about two tiers of sheaves, the sheaves being rotatable independently of each other, utilizing said sheaves to make electrical connection with the wire and passing the electrolyte rapidly past the runs of wire between the sheaves.

24:. The method of electrolytically depositing metal on Wires or other flexible cathodes, which comprises passing the wires in helicoidal form about two tiers of sheaves, said tiers being substantially out of the electrolyte and the sheaves of each tier being free to rotate relative to the cooperating sheaves of each tier, thereby to equalize the strain on said wire, and circulating active electrolyte past the runs of wire between said sheaves.

25b The method of making metal-coated wire, which comprises carrying on electrolytic deposit of metal in a rapidly flowing stream of electrolyte, while the wire is drawn through the stream, and subsequently freeing the wire from the electrolyte by subj ect- 10 ing the same to the heating and cleansing action of steam.

In testimony name to this specification,

MATTHEW M. MERRITT.

whereof, I have signed my 

